Core Internet Technology Is Vulnerable

Researchers found a serious security flaw that left core Internet technology vulnerable to hackers, prompting a secretive effort by international governments and industry experts in recent weeks to prevent global disruptions of Web surfing, e-mails and instant messages.

Experts said the flaw, disclosed Tuesday by the British government, affects the underlying technology for nearly all Internet traffic. Left unaddressed, they said, it could allow hackers to knock computers off line and broadly disrupt vital traffic-directing devices, called routers, that coordinate the flow of data among distant groups of computers.